Industrial handling of a wide variety of goods such as building materials, machinery and packaged goods, usually employ the use of palettes of wood, metal or plastic which provides a stable base for the goods. In addition, such palettes provide a space beneath the goods so that they may more readily be lifted by a hoist to be transported.
In some cases, such palettes are not necessary. Stacks of product, eg. building blocks, define horizontal passageways for lifting on a hoist, and are sufficiently stable to be stacked without palettes. Such palettes and stacks will vary in size and also in design. They will usually provide narrow passageways through which separate prongs of a fork-like lifting device may be inserted. Variations exist in different palettes or products and the spacing between such passageways differs. It has been proposed to provide lifting forks with a capability for varying the spacing between the individual prongs. In this way, one lifting fork assembly can be used to lift various different types of palettes.
In addition to this problem, however, the size and shaping of the various loads carried on such palettes is subject to wide variation. Lifting forks of this type are used on lifting cables and it is essential that the load will be more or less balanced or centred beneath the axis of the cable.
The general design of such lifting forks of this type, employs a number of more or less horizontal prongs, attached to some sort of vertical frame work adapted to extend upwardly on one side of the palette.
In order to balance the load beneath a hoisting cable, a generally L-shaped balance bar is provided attached to the upper end of the vertical framework, so that the hoist cable may be attached more or less centrally with regard to the load.
Where the load on the palette will always be the same height and shape, then the vertical framework and the balance bar can be designed specifically to suit the load.
Changes in the size or shape of the load, would however, require the actual lifting fork to be changed to accommodate it and may require changes in the balance bar.
It is therefore a general objective of the invention to provide a universal lifting fork, in which both the spacing between the prongs may be varied to suit different types of product or palette, and in which the height of the side frame may be varied, and also in which the length of the balance bar may also be effectively changed, so as to suit different products or palettes, and loads on such palettes of varying shapes, by a system of adjustments incorporated in the lifting fork itself.
More particularly, it is an objective of the invention to provide a universal lifting fork with a plurality of lifting prongs arranged on a generally horizontal support means, with such lifting prongs being moveable along such support means.
More particularly, it is an objective of the invention to provide such a universal lifting fork in which the side frame incorporates a single column portion, with adjustment means incorporated in such column portion whereby the same may be extended or retracted to vary the height of the frame.
More particularly, it is an objective of the invention to provide such a universal lifting fork assembly in which the L-shaped balance bar is provided with a slideable attachment means for interconnection to a hoisting cable, and means for locking such slideable attachment means in a variety of different positions, thereby effectively varying the length of the balance bar for purposes of balancing the load.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to an forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated and described preferred embodiments of the invention .